The body surfaces of insects are marvels of natural engineering, displaying a remarkable array of adaptations that enable them to thrive in diverse environments . Insects have developed a variety of mechanisms to cope with the challenges posed by their habitats, from specialized structures for attachment and movement to unique features that enhance survival and reproductive success . These adaptations may provide valuable insights for biomimetic and bioinspired technological advancements . Hence, understanding these mechanisms not only sheds light on the evolutionary ingenuity of insects but also offers innovative solutions and technological applications.

The cuticle of Hymenoptera exhibits several fascinating properties.

The cuticle surfaces of some species reduce friction and wear, inspiring the development of low-friction materials and coatings. By mimicking these natural textures, it is possible to create synthetic materials that exhibit similar friction-reducing properties, leading to significant advancements in mechanical efficiency and durability. For instance, low-friction coatings inspired by Hymenoptera cuticles can be applied to materials to reduce wear and tear, thereby enhancing performance, and extending the lifespan of the material.

Surface roughness can have beneficial effects on the overall aerodynamic characteristics of artificial surfaces, such as rough coatings on high-speed trains , dimples on golf balls , and shark skin denticles on aircrafts . Some micromachines can also benefit from micro- and nanostructures that create roughness on surfaces and influence aerodynamics and heat transfer . The sculptured and thick cuticle of some hymenopterans is also associated with increased resistance to fractures and high pressures and may also potentially reduce water loss . Alternative hypotheses yet to be tested for the function of such complex cuticle sculpturing is the air drag reduction during flight, as many hymenopterans (e.g., chrysidids, scelionids, and mutillids) have dimples on the cuticle that might have the same aerodynamic effect as those on golf balls . Setose cuticle in hymenopterans also exhibits an interesting function, namely, reducing the accumulation and deposition of particles .

Similarly, in the medical field, these coatings can be used on surgical instruments and prosthetics to minimize friction against biological tissues, reducing discomfort and improving the functionality of medical devices. Furthermore, in the field of electronics, low-friction surfaces can prevent the wear of moving parts in devices such as hard drives and printers, ensuring longer operational life and reliability. The mechanisms behind the cuticle’s friction-reducing properties also include the ability to repel dust and contaminants, which further extends the applications of these biomimetic materials. For instance, the cuticle of sawfly larvae has complex nanostructures and wax crystals that result in hydrophobicity . By incorporating these properties, manufacturers may develop self-cleaning surfaces that maintain their low-friction characteristics even in harsh environments. This feature is particularly valuable in aerospace applications, where equipment is often exposed to extreme conditions.

Cuticle coloration in Hymenoptera may be achieved through either structural coloration or pigments, the latter being essentially melanin (eumelanin and/or pheomelanin) (but see for other pigments). Especially structural coloration provides a wealth of inspiration for creating vivid, durable colors without the use of dyes. This natural phenomenon involves the manipulation of light by micro- and nanostructures on the cuticle (e.g., epicuticular multilayer reflectors), which can produce brilliant and iridescent colors . The examples range from the metallic wings of some bees to the striking iridescent colors of wasps . Blue coloration is hard to find in nature because blue pigments are rare; hence, animals tend to evolve structural coloration that reaches blue hues, like in carpenter bees . Some species have ultrablack cuticles that absorb nearly all incident light (Lopez et al., this volume), a feature that can be used to create highly efficient light-absorbing materials for solar panels . Understanding and mimicking these biological systems can lead to significant advancements in various fields, including materials science, fashion, and environmental sustainability .

In materials science, the principles of structural coloration can be applied to develop colorfast materials that do not fade over time . Traditional pigments and dyes can degrade under exposure to light, heat, and chemicals, but structurally colored materials maintain their vibrancy indefinitely. This has potential applications in creating long-lasting paints, coatings, and fabrics, reducing the need for frequent replacements and repainting, thus conserving resources, and reducing waste . The fashion industry can also benefit greatly from such biomimetic and bioinspired surfaces . By incorporating structural coloration into textiles, designers can create clothing and accessories with striking, iridescent hues that do not rely on chemical dyes . This can lead to more sustainable fashion practices, as the production of synthetic dyes often involves toxic chemicals and generates significant environmental pollution . Structurally colored fabrics would offer a greener alternative, aligning with the growing demand for eco-friendly fashion.

Furthermore, structural coloration can inspire the creation of innovative security features . The unique optical effects of these natural structures are difficult to replicate and counterfeit, making them ideal for use in anti-counterfeiting measures. Banknotes, identification cards, and high-value documents can incorporate structural coloration to enhance security and prevent forgery, leveraging the complexity and uniqueness of these bioinspired designs. In the field of consumer electronics, the vibrant and durable colors produced by structural coloration can be used to create more aesthetically pleasing and durable electronic devices. Smartphone cases, laptops, and other gadgets can feature iridescent colors that do not wear off or fade, enhancing both their appearance and longevity. This not only improves the user experience but also contributes to a reduction in electronic waste, as devices retain their visual appeal over a longer period. The techniques to create biomimetic materials with color producing mechanisms inspired by insects already exist and applications of such technology have several possibilities.

The body surface of insects is equipped with hairs (sensu lato) with different morphologies. These structures may first be categorized into two main types, that is, setae, which have a socket (which originates from an adjacent cell) and microtrichia (not socked and thus originating from one cell) . Such tiny structures belong to two main functional types. They are either mechanosensory and belong to the peripheral nervous system or they have no sensing role and serve to prevent wetting of, for example, wings and legs . Other functions include the detection of airflow patterns, for example, through trichoid sensilla on the compound eyes of honeybees , which are important to maintain and coordinate flight. In general, the head capsule of Hymenoptera is densely covered with hairs and may be a ground-plan feature of Hymenoptera and a potential autapomorphy . While the reason for such trait is still unknown, the fact that another order, the Diptera, also including mostly quick-flying insects, show the same pattern, may suggest a relationship with optimization of flight behavior. Evidence on structures and functions of some of these non-sensory hairs in ants and bees suggest intriguing applications in biomimetics.

In ant larvae, other non-sensory functions of hairs include, for example, ensuring ventilation at the body surface and larval clumping, the latter function through special “hooked” hairs . Adult ants of the tropical tribes Basicerotini and Stegomyrmecini, in contrast, possess brush hairs on the body that capture minute soil particles, camouflaging themselves with the soil surface , while adult desert ants have special long and curved hairs on the lower surface of the head and mouthparts, which improve soil digging and soil carrying .

In the honeybee, a special microscale hairy compliant texture on abdominal surfaces reduces friction, which is relevant considering that the abdominal sections, by undergoing many reciprocating motions, are at risk of wear or abrasion . Ocular hairs in honeybees reduce airflow at the eye surface by up to 90%, deflecting incoming air and create a zone of stagnant air, potentially helping in the deployment of sensors outdoors, where they are strongly subjected to airborne dust .

Figure 4: (A) SEM image of a hymenopteran antenna (Anthidium oblongatum). (B) SEM images of male antennal sensilla of Ibalia leucospoides. (C) SEM images of female antennal sensilla of Cerceris rubida. Pe: pedicel; Sc: scape; Fl: flagellum; Pl: placoid sensilla; Tr: trichoid sensilla.

Wings: In order to fulfill their essential functions, insect wings must effectively transmit force from the muscles at their base to the surrounding air, generate lift, and uphold structural integrity without deformation . Hence, wings need to be lightweight, flexible, and resilient, rendering them captivating subjects for biomimetic materials research . For instance, an examination of the nanomechanical properties of membranous wings in Chinese bees (Apis cerana cerana) reveals a synergistic interplay between veins and membranes, facilitating efficient load transmission and resulting in exceptional mechanical performance and structural stiffness . Research on biological membranes, inspired by the superior structures of insect wings, holds potential for advancements in various sectors, including medical, construction, aviation, and automotive industries .

Research on hymenopteran wings remains limited, with many groups still requiring fundamental studies on their properties. Exploring other Hymenoptera species could yield valuable insights. For instance, the females of scoliid wasps, solitary parasitoids of scarab beetle larvae, dig into the ground to locate these larvae. This could inspire the development of wings for exploration and rescue drones, modeled after the scoliid wasps’ wings, offering high maneuverability, durability, and efficiency in flight and underground across varied terrains. Similarly, Vespidae with elongated bodies possess pointed wings for enhanced maneuverability, while stouter species have rounded wings for potentially higher flight speeds . This variation could inform the design of modular drones capable of altering wing shapes to optimize either maneuverability or flight speed as needed. Additionally, the design of these devices could be enhanced by a unique feature observed in ensign wasps (Afrevania and Trissevania, Evaniidae) . These wasps exhibit a sophisticated ability to fold their forewings along two intersecting fold lines, creating a four-plane wing folding mechanism . By incorporating a similar four-plane wing folding mechanism, drones could achieve enhanced compactness and versatility, allowing for easy transport and storage, as well as efficient adaptation to various environments and mission requirements.

Figure 5: SEM image of wing bristles in a microwasp Megaphragma polilovi. (A) Dorsal view and (B) lateral view. Scale bars: 100 µm. Both figures are from and were reprinted by permission from Springer Nature from the book “At the Size Limit - Effects of Miniaturization in Insects” (chapter “Structure of the Principal Groups of Microinsects. VI. Trichogrammatid Wasps (Hymenoptera: Trichogrammatidae)” by A. A. Polilov), Copyright 2016 Springer International Publishing Switzerland. This content is not subject to CC BY 4.0.

The wing-to-wing coupling mechanism in Hymenoptera functions as a multifaceted joint, linking the forewing’s rolled membrane to the hindwing’s hook structures, enabling synchronized movement and improved aerodynamic performance . This mechanism is composed of a rolled membrane positioned at the trailing edge of the forewing, accompanied by small hooks (or hamuli) arranged in a line along the leading edge of the hind wing, all attached to a vein at the leading edge of the hind wing where the hooks are embedded . These hooks are movable and exhibit an elastic base to ensure the high mobility of wings . The coordinated movement of wings facilitated by this mechanism enables synchronized action and improved aerodynamic performance, while also allowing for decoupling during periods of rest, thereby avoiding aerodynamic interference and ensuring optimal flight dynamics. Computational models also indicate that the wing-to-wing coupling mechanism in Hymenoptera results in increased lift and drag, with the drag experiencing a higher rate of increase .

Despite their seemingly delicate nature and occupancy of a mere ≈0.2% of the total wing area, these hooks play a crucial role in continuously transferring forces between the wings, withstanding forces up to 180 times the insect’s body weight and 40 times the aerodynamic forces encountered during flight . This robust design of the coupling mechanism is essential for maintaining functionality, particularly in scenarios involving frequent collisions, where it must endure forces surpassing typical flight stresses . Additionally, the microstructural properties of the wings contribute to their hydrophobicity and anti-fouling capabilities, which can be applied to the development of self-cleaning surfaces and materials resistant to biofouling in marine environments.

Figure 6: Structures on the leg of Hymenoptera. (A) Adhesive pads in ants (Messor wasmanni) and (B) antenna cleaner (strigil) of velvet ants (Traumatomutilla bifurca). Both figures were taken by Stanislav N. Gorb and were used with permission. This content is not subject to CC BY 4.0.

In other instances, the presence of curved spines or hair on the tarsomeres enhances locomotion on irregular surfaces by penetrating the microdevices of the substrate, providing thousands of interlocking points that contribute to overall friction . For example, weaver ants, renowned for their ability to cling to vertical surfaces and construct large leaf nests, utilize dense arrays of tarsal friction hairs on their tarsomeres to boost adhesion on heavily sculpted surfaces . Similarly, females of Anastatus bifasciatus (Eupelmidae) employ these structures to achieve a firm grip on the uneven surfaces of host eggs . These examples highlight the potential for biomimetic applications of such structures in developing advanced adhesive technologies and improving robotic mobility on uneven terrain and in microgravity environments .

Corbicula: Several bee species (e.g., honey bees, bumble bees, and orchid bees) exhibit a pollen basket on the hindlegs called corbicula . Bees pack pollen grains along with vegetal resins and nectar in their corbiculae and take flight with this material without losing the attachment force even under great air drag and movement-derived forces . Corbiculate bees are one of the most effective pollinator groups worldwide. Up to now, there are no studies on the potential replication of such strategy in biomimetics; however, one might suggest that the successful evolutionary history of the corbicula may be a source of inspiration for technology. Potentially, the corbicula, as other structures mentioned here, may inspire the creation of materials and innovations to carry viscous substances across large distances.

Micro-grooming tools: The maintenance of clean and functional body surfaces is crucial for insects. The typical mode of grooming occurring in Hymenoptera consists in scraping (one-directional movement of one structure against another), rubbing (two-directional movement of one or both structures in contact) or nibbling (an antenna or leg is taken into the inner mouthparts, essentially mandibles or legs) . About 30 distinct types of grooming movements are actually recognized for the order .

Figure 7: Perforating structures on the metasoma of Hymenoptera. (A, B) Ovipositor of Neralsia sp. and Andricus coriarius. (C, D) Sting of Oxybelus haemorrhoidalis. La: lancet; St: stylet; Ba: lateral barbed structure.

The ovipositor of certain parasitic wasps, such as those in sawflies wasp and ichneumon wasps has inspired the development of a prototype of a drill rasp designed for excavating femoral cavities, tailored for snugly inserting cementless hip prosthesis stems . Apart from their highly specialized form, also the elemental structure of this organ evolved to increase drilling ability while limiting abrasion and wear. Indeed, trace metals such as Zn, Mn, and Cu were variably found within the cuticle matrix of Hymenoptera ovipositors and stings . The mechanics of the ovipositor, characterized by its flexibility, strength, and the ability to penetrate tough materials with minimal force, offer a model for designing minimally invasive surgical instruments and precision technology . Still in the medical field, the ovipositor’s unique properties may lead to the development of highly specialized probes and needles for diagnostic and therapeutic purposes . These bioinspired tools can navigate through soft tissues with minimal damage, mimicking the ovipositor’s ability to penetrate substrates smoothly and efficiently . Hence, drawing inspiration from ovipositors, these innovations may enhance medical procedures by amplifying precision, minimizing recovery periods, and augmenting patient outcomes, particularly in scenarios where maneuverability and accuracy are paramount.

In addition to medical applications, the ovipositor’s design principles have broader implications for engineering and technology. The ovipositor’s ability to penetrate tough materials with minimal force inspires the development of tools and machinery that require high precision and efficiency . For instance, researchers at the Surrey Space Centre have drawn inspiration from the wood wasp to create a drilling system that is simple, robust, lightweight, and efficient for use on extra-terrestrial subsurface exploration . The ovipositor’s structural and functional characteristics can inform the design of robotic systems. Robots equipped with ovipositor-inspired appendages can perform delicate tasks that require both strength and precision, such as handling fragile objects or performing intricate assembly operations . Therefore, drilling and cutting tools modeled after the ovipositor can achieve greater accuracy and reduce wear and tear, leading to longer lasting and more effective equipment. This innovation can be applied in various industries, from construction to manufacturing, enhancing productivity, and reducing operational costs.

In environmental science, the study of ovipositor mechanics can contribute to the development of sustainable technologies for soil sampling and ecological monitoring. Devices modeled after the ovipositor can penetrate the ground to collect soil samples without causing significant disturbance to the ecosystem. This capability is important for monitoring soil health, studying underground biodiversity, and assessing environmental impacts, providing researchers with valuable data while preserving natural habitats.

Delivery systems: Strength and efficiency of the ovipositor also offer insights into creating advanced drug delivery systems . These systems can deliver medications directly to targeted areas within the body, improving the efficacy of treatments while minimizing side effects . By emulating the ovipositor’s ability to penetrate and deliver substances precisely, researchers have developed microneedles . This approach is especially beneficial for administering vaccines and treatments for chronic conditions, providing a less invasive and more patient-friendly alternative to traditional methods.

Figure 8: Scanning Electron Microscopy image showing the stridulatory organ in male velvet ants. (A, B). Myrmilla capitata; (C, D). Nemka viduata. Fi: file; Ri: ridges. Sound is produced by rubbing files and ridges against each other.

Certain hymenopterans are capable of emitting stridulatory sounds at high frequencies, including ultrasound (≥20 kHz) . The design of medical devices could greatly benefit from innovations inspired by these stridulation mechanisms. Ultrasound technology has demonstrated significant potential in diagnostic imaging and ultrasound-responsive drug delivery . Ultrasound technology is particularly promising for cancer treatment and disease modulation, as it facilitates the delivery of therapeutic agents such as genetic material, proteins, and chemotherapeutics . Incorporating principles from the finely tuned frequency production observed in Hymenoptera could significantly enhance this technology, resulting in more precise and effective ultrasound equipment, thus improving patient outcomes in both diagnostics and treatment. Furthermore, studying the use of acoustic signals in hymenopterans may offer valuable inspiration for future research, as these context-dependent signals can modulate the production or inhibition of chemical signals in other individuals .

Moreover, the precise control over vibration frequencies observed in stridulation can inspire advancements in industrial applications where vibration control is essential. This includes machinery that operates more quietly and efficiently, reducing noise pollution and wear on components. Additionally, the principles of stridulation could be applied to develop sensors and actuators that are more sensitive and responsive, improving the performance of various mechanical and electronic systems.

Metasomal shape: The morphology of the metasoma in Hymenoptera offers significant potential for biomimetic applications, particularly within aerospace engineering. For instance, the segmented and flexible structure of a bee’s metasoma facilitates efficient and dynamic flight maneuvers . Bees optimize their aerodynamic performance and maneuverability through biomorphic adjustments to their shape . This adaptable structure can inspire the development of aerospace vehicles with enhanced axial scalability and bending properties . Incorporating a morphing structure inspired by the Hymenoptera metasoma could lead to the creation of supermaneuverable flight systems, contributing to advanced designs for aircraft and unmanned aerial vehicles, and reducing aerodynamic drag .

Furthermore, the metasoma of bees can dissipate residual flight energy during landing , and the shape of the metasoma can influence maneuverability and flight speed in wasps. Integrating these biological principles could result in vehicles capable of agile and precise movements and increased stability in turbulent conditions. Despite these promising possibilities, the shape and surface characteristics of the hymenopteran metasoma remain underexplored, and families with unique metasomal forms still lack basic research. For instance, cuckoo wasps (Chrysididae) possess a concave metasomal venter, enabling them to roll into a ball when threatened . Hatchet wasps (Evaniidae) exhibit short and flag-shaped metasoma that moves up and down as they walk, resembling a flag or hatchet. In pelecinid wasps (Pelecinidae), the elongated metasoma allows them to locate and deposit eggs in subterranean hosts . This unique metasomal morphology provides various adaptive advantages and can inspire innovations in designs.

Prey-carrying and prey-catching mechanisms: Some groups of predatory wasps hunt prey and subsequently transport it in flight to the nests, using either mandibles, legs or even the sting to keep the prey. Most predatory wasps use front and mid legs to carry the prey, while a few wasp species hold their prey only with the hind legs . The efficient prey-loading mechanisms of some of these Hymenopteran species, that can even carry lift loads greater than the theoretical maximum as expected by their body mass and wing morphology , can inspire the design of robotic systems for material handling and transport, enhancing the efficiency of automated loading and unloading processes in various industries. By holding the prey on the sting, some species of Oxybelus (Crabronidae) have effectively freed all three pairs of legs for other purposes . This peculiar way to carry the prey impaled on the aculeus is made possible through the special curvature and surface sculpture of sting elements (notably, barbs on the distal part of the lateral surface of the first valvula) , as well as by modifying the wings lift coefficient between the anterior and posterior wings movement .

Hymenoptera exhibit interlocking structures in their bodies that provide stability and flexibility. These structures can inform the design of modular and reconfigurable systems in robotics and materials science, especially for drones that must carry attachable items. Phoretic copulation is probably the main inspiration source . Similar interlocking mechanisms can be found between male mouthparts and female head and mesosome for phoretic copulation (e.g., some mutillids) , and the same happens for male–female genitalia (e.g., bethylids, thynnids) . Another example is the labrum–maxillae interlocking mechanism exclusive of ants .

Mites can be found in various locations on the bodies of hymenopterans . However, some species of bees and wasps have evolved specialized structures known as acarinaria, which facilitate the safe transport of mites . The acarinarium can be located in one or more areas on the insect’s body surface such as the propodeum, mesosoma, just below the apex of the first metasomal tergum, and in some cases, within the genital chamber of species such as Ancistrocerus antilope (Vespidae) . These structures could be integrated into drones, plant leaves, or stems, providing secure havens for biocontrol agents. This approach would naturally manage pest populations, reducing the need for chemical pesticides and promoting sustainable farming practices .